The present invention relates to protein kinase inhibitors, compositions comprising such inhibitors, and methods of use thereof. More particularly, the invention relates to inhibitors of Aurora protein kinase. The invention also relates to pharmaceutical compositions, as well as to methods of treating diseases associated with protein kinases, especially diseases associated with Aurora A and Aurora B, such as cancer and further proliferative diseases.
Protein kinases represent a large family of proteins, which play a central role in the regulation of a wide variety of cellular processes, thus maintaining control over cellular function. A partial list of such kinases includes Akt, Axl, Aurora A, Aurora B, dyrk2, epha2, fgfr3, flt-3, vegfr3, igf1r, IKK2, JNK3, Vegfr2, MEK1, MET, P70s6K, Plk1, RSK1, Src, TrkA, Zap70, cKit, bRaf, EGFR, Jak2, PI3K, NPM-Alk, c-Abl, BTK, FAK, PDGFR, TAK1, LimK, Flt3, Flt1, PDK1 and Erk. Inhibition of such kinases has become an important therapeutic target.
Many diseases are associated with abnormal cellular responses triggered by protein kinase-mediated events. These diseases include autoimmune diseases, inflammatory diseases, neurological and neurodegenerative diseases, cancer, cardiovascular diseases, allergies and asthma, Alzheimer's disease or hormone-related diseases. Accordingly, there has been a substantial effort in medicinal chemistry to find protein kinase inhibitors that are effective as therapeutic agents.
The compounds of the invention are novel, selective, and highly potent adenosine triphosphate (ATP) competitive inhibitors of Aurora kinases (A, B and C). The Aurora family of conserved serine/threonine kinases perform essential functions during cell division. The three mammalian paralogues are very similar in sequence, but differ significantly in their localization, function, substrates and regulatory partners. Aurora A is mainly associated with the spindle poles during mitosis, where it is required for centrosome separation and maturation (Sausville EA. Aurora kinases dawn as cancer drug targets, Nat. Med., (2004)10: 234-235 (2004). Spindle assembly requires that targeting protein for XKLP 2 (TPX2) targets Aurora A to spindle pole microtubules through a mechanism that requires Ran-GTP (Marumoto T, Zhang D, Saya H. Aurora A—A guardian of poles, Nature, (2005) δ 42-50 (2005). Aurora A also functions in meiosis promoting oocyte maturation, polar-body extrusion, spindle positioning and exit from metaphase I. Regulation of Aurora A occurs through phosphorylation/dephosphorylation and degradation. Protein phosphatase 1 negatively regulates Aurora and this interaction is modulated by TPX2. Aurora B is a chromosomal-passenger protein with multiple functions in mitosis. Inner centromere protein (INCENP) and survivin, two other components of the passenger complex, function as targeting and regulatory factors for the kinase (Bishop J D and Shumacher J M. Phosphorylation of the Carboxyl Terminus of Inner Centromere Protein (INCENP) by the aurora B Kinase Stimulates aurora B Kinase Activity, J. Biol. Chem. (2002) 277:27577-27580. Aurora B is required for phosphorylation of histone H3, targeting of condensin and normal chromosome compaction. It has also been recently shown to be essential for chromosome biorientation, kinetochore-microtubule interactions and the spindle-assembly checkpoint. Aurora B is essential for completion of cytokinesis. Myosin II regulatory chain, vimentin, desmin and glial fibrillary acidic protein are among its cleavage furrow substrates. Aurora B phosphorylates MgcRacGAP, transforming it into an activator of RhoA in the contractile ring (Minoshima Y, Kawashima T, Hirose K, Tonozuka Y, Kawajiri A, Bao Y, Deng X, Tatsuka M, Narumiya S, May W Phosphorylation by aurora B converts MgcRacGAP to a RhoGAP during cytokinesis. Dev. Cell, (2003) 4:549-560. Much less is known about Aurora C kinase, other than that it seems to be preferentially expressed in meiotic cells. During the cell cycle, Aurora kinases travel to their subcellular targets aided by their binding partner-substrates, INCENP, survivin and TPX2. This provides an additional level of regulation that might be essential for the choreography of mitotic events.
Aurora A and B kinases are frequently elevated in human cancers making them attractive targets for therapeutic intervention. Small molecule inhibitors of Aurora kinases have recently been reported, but their effect on cytokinesis has yet to be investigated in detail. For example a high selective and potent small-molecule inhibitor of Aurora kinases, VX-680, blocks cell-cycle progression and induces apoptosis in a diverse range of human tumor types. This compound causes profound inhibition of tumor growth in a variety of in vivo xenograft models, leading to regression of leukemia, colon and pancreatic tumors at well-tolerated doses (Harrington E A, Bebbington D, Moore J, Rasmussen R K, Ajose-Adeogun A O, Nakayama T. Graham J A, Demur C, Hercend T, Diu-Hercend A, Su M, Golec J M, Miller K M VX-680, a potent and selective small-molecule inhibitor of the aurora kinases, suppresses tumor growth in vivo, Nat. Med., (2004) 10: 262-267. Another novel cell cycle inhibitor, JNJ-7706621, showed potent inhibition of several cyclin-dependent kinases (CDK) and Aurora kinases and selectively blocked proliferation of tumor cells of various origins, but was about 10-fold less effective at inhibiting normal human cell growth in vitro. In human cancer cells, treatment with JNJ-7706621 inhibited cell growth independent of p53, retinoblastoma, or P-glycoprotein status; activated apoptosis; and reduced colony formation. At low concentrations, JNJ-7706621 slowed the growth of cells and at higher concentrations induced cytotoxicity. Inhibition of CDK1 kinase activity, altered CDK1 phosphorylation status, and interference with downstream substrates such as retinoblastoma were also shown in human tumor cells following drug treatment. JNJ-7706621 delayed progression through G1 and arrested the cell cycle at the G2-M phase (Emanuel S, Rugg C A, Gruninger R H, Lin R, Fuentes-Pesquera A, Connolly P J, Wetter S K, Hollister B, Kruger W W, Napier C, Jolliffe L, Middleton S A, The in vitro and in vivo effects of JNJ-7706621: A dual inhibitor of cyclin-dependent kinases and aurora kinases, Cancer Res., (2005) 65:9038-9046). Additional cellular effects due to inhibition of Aurora kinases included endoreduplication and inhibition of histone H3 phosphorylation. In a human tumor xenograft model, several intermittent dosing schedules were identified that produced significant antitumor activity.
As noted above, Aurora kinases are overexpressed in certain types of cancers, including colon, breast, and other solid-tumor cancers. The genes encoding the Aurora B and A kinases tend to be amplified in certain types of cancers, while the gene encoding the Aurora C kinase resides in a region of the chromosome that is subject to rearrangement and deletion. Aurora A has been associated with a variety of malignancies, including primary colon, colorectal, breast, stomach, ovarian, prostate, and cervical cancer, neuroblastoma, and other solid-tumor cancers (Warner et al. (2003) Molecular Cancer Therapeutics 2:589-95).
Hauf et al. (J. Cell. Biol. (2003) 161:281-294) identified the indolinone (Hesperadin) as an inhibitor of Aurora B, which causes cells to enter anaphase with monooriented chromosomes, having both sister kinetochores attached to a single spindle pole (a condition known as syntelic attachment).
Ditchfield et al. (J. Cell. Biol. (2003) 161:267-280) described ZM447-439 ((4-(4-(N-benzoylamino)anilino)-6-methoxy-7-(3-(1-morpholino)propoxy) quinazoline), an Aurora kinase inhibitor which interferes with chromosome alignment, segregation, and cytokinesis.
The present invention specifically relates to compounds of the formula I which inhibit, regulate and/or modulate signal transduction by Aurora kinase, to compositions which comprise these compounds, and to processes for the use thereof for the treatment of Aurora kinase-induced diseases and complaints, such as angiogenesis, cancer, tumour formation, growth and propagation, arteriosclerosis, ocular diseases, such as age-induced macular degeneration, choroidal neovascularisation and diabetic retinopathy, inflammatory diseases, arthritis, thrombosis, fibrosis, glomerulonephritis, neurodegeneration, psoriasis, restenosis, wound healing, transplant rejection, metabolic diseases and diseases of the immune system, also autoimmune diseases, cirrhosis, diabetes and diseases of the blood vessels, also instability and permeability and the like in mammals.
Solid tumours, in particular fast-growing tumours, can be treated with Aurora kinase inhibitors. These solid tumours include monocytic leukaemia, brain, urogenital, lymphatic system, stomach, laryngeal and lung carcinoma, including lung adenocarcinoma and small-cell lung carcinoma.
The present invention is directed to processes for the regulation, modulation or inhibition of Aurora kinase for the prevention and/or treatment of diseases in connection with unregulated or disturbed Aurora kinase activity. In particular, the compounds of the formula I can also be employed in the treatment of certain forms of cancer. The compounds of the formula I can furthermore be used to provide additive or synergistic effects in certain existing cancer chemotherapies, and/or can be used to restore the efficacy of certain existing cancer chemotherapies and radiotherapies.
The compounds of the formula I can furthermore be used for the isolation and investigation of the activity or expression of Aurora kinase. In addition, they are particularly suitable for use in diagnostic methods for diseases in connection with unregulated or disturbed Aurora kinase activity.
It can be shown that the compounds of the invention have an antiproliferative action in vivo in a xenotransplant tumour model. The compounds according to the invention are administered to a patient having a hyperproliferative disease, for example to inhibit tumour growth, to reduce inflammation associated with a lymphoproliferative disease, to inhibit transplant rejection or neurological damage due to tissue repair, etc. The present compounds are suitable for prophylactic or therapeutic purposes. As used herein, the term “treatment” is used to refer to both prevention of diseases and treatment of pre-existing conditions. The prevention of proliferation is achieved by administration of the compounds according to the invention prior to the development of overt disease, for example to prevent the growth of tumours, prevent metastatic growth, diminish restenosis associated with cardiovascular surgery, etc. Alternatively, the compounds are used for the treatment of ongoing diseases by stabilising or improving the clinical symptoms of the patient.
The host or patient can belong to any mammalian species, for example a primate species, particularly humans; rodents, including mice, rats and hamsters; rabbits; horses, cows, dogs, cats, etc. Animal models are of interest for experimental investigations, providing a model for treatment of human disease.
The susceptibility of a particular cell to treatment with the compounds according to the invention can be determined by in vitro tests. Typically, a culture of the cell is combined with a compound according to the invention at various concentrations for a period of time which is sufficient to allow the active agents to induce cell death or to inhibit migration, usually between about one hour and one week. In vitro testing can be carried out using cultivated cells from a biopsy sample. The viable cells remaining after the treatment are then counted.
The dose varies depending on the specific compound used, the specific disease, the patient status, etc. A therapeutic dose is typically sufficient considerably to reduce the undesired cell population in the target tissue while the viability of the patient is maintained. The treatment is generally continued until a considerable reduction has occurred, for example an at least about 50% reduction in the cell burden, and may be continued until essentially no more undesired cells are detected in the body.
For identification of a signal transduction pathway and for detection of interactions between various signal transduction pathways, various scientists have developed suitable models or model systems, for example cell culture models (for example Khwaja et al., EMBO, (1997), 16: 2783-93) and models of transgenic animals (for example White et al., Oncogene, (2001), 20: 7064-7072). For the determination of certain stages in the signal transduction cascade, interacting compounds can be utilised in order to modulate the signal (for example Stephens et al., Biochemical J., (2000), 351:95-105). The compounds according to the invention can also be used as reagents for testing kinase-dependent signal transduction pathways in animals and/or cell culture models or in the clinical diseases mentioned in this application.
Measurement of the kinase activity is a technique which is well known to the person skilled in the art. Generic test systems for the determination of the kinase activity using substrates, for example histone (for example Alessi et al., FEBS Lett. (1996), 399(3): 333-338) or the basic myelin protein, are described in the literature (for example Campos-González, R. and Glenney, Jr., J. R., J. Biol. Chem. (1992), 267:14535).
For the identification of kinase inhibitors, various assay systems are available. In scintillation proximity assay (Sorg et al., J. of. Biomolecular Screening, (2002), 7:11-19) and flashplate assay, the radioactive phosphorylation of a protein or peptide as substrate with γATP is measured. In the presence of an inhibitory compound, a decreased radioactive signal, or none at all, is detectable. Furthermore, homogeneous time-resolved fluorescence resonance energy transfer (HTR-FRET) and fluorescence polarisation (FP) technologies are suitable as assay methods (Sills et al., J. of Biomolecular Screening, (2002) 191-214). Another possibility is the use of a caliper test as exemplified in example 151.
Other non-radioactive ELISA assay methods use specific phospho-antibodies (phospho-ABs). The phospho-AB binds only the phosphorylated substrate. This binding can be detected by chemiluminescence using a second peroxidase-conjugated anti-sheep antibody (Ross et al., 2002, Biochem. J.).
There are many diseases associated with deregulation of cellular proliferation and cell death (apoptosis). The conditions of interest include, but are not limited to, the following. The compounds according to the invention are suitable for the treatment of various conditions where there is proliferation and/or migration of smooth muscle cells and/or inflammatory cells into the intimal layer of a vessel, resulting in restricted blood flow through that vessel, for example in the case of neointimal occlusive lesions. Occlusive graft vascular diseases of interest include atherosclerosis, coronary vascular disease after grafting, vein graft stenosis, peri-anastomatic prosthetic restenosis, restenosis after angioplasty or stent placement, and the like.
Accordingly, kinase inhibitors, particularly inhibitors of Aurora kinases, are of particular interest in treating certain disorders, including cancer and other proliferative diseases. Compounds exhibiting such inhibition are of particular value.